Harriet is in the dock for gross negligence manslaughter as the families' private prosecution finally arrives in court. Angela and the others have nearly bankrupted themselves to fund the case. Will it all have been worth it? Polly fears for Leona, who wants to give evidence, but it is her relationship with Iwan that presents her with the most challenging questions. Final episode of Jack Thorne's drama, starring Sarah Lancashire, Joanna Scanlan, Mark Lewis Jones and Sidse Babbett Knudsen.